Friday, February 25, 2005

ROI on Architecture

Bill Venners has started an interesting thread on software architecture and ROI at Artima.Here is my response to the posting:There are two forces that a software usually has to reckon with. Changes in business requirements and changes in technology. Let's say we build an ERP system. Some business rules in the accounting module might have to be modified due to changes in tax laws. Parhaps the client might want to produce more reports or change some existing ones. The client might want to change the UI. Brainstorming with domain experts and clients will most likely help us make a comprehensive (though not all-encompassing) list of requirements that can change in the next let's say three years. With some further thought we may also be able to attach a probablity of change. If we incorporate enough flexibility for high probablity changes then we will get a good return on investment on the architecture. I think this is the middle ground between an overly simplified architecture and a very complex one. The other force that acts on our architecture is changes in technology. Had we created our ERP system with an amateuer homegrown MVC kernel, then we might at some point feel the need to use Struts or an equivalent framework. The refactoring effort will depend on our choices of classes and their responsibilities. If we have used good OO priciples and ensured that each class has a coherent set of responsibilities and the methods are well structured, then we might actually be able to reuse a large part of our existing code base with minor modifications in the new architecure. What if we have to face a drastic technological change, which will render our current code base useless? This is possible though not very likely. Technological changes do not usually happen overnight. There is enough indication before a promising technology becomes mainstream. If we adopt the practice of constant refactoring then we should be able to adapt to the new tecghnology gradually.I think there is a definite value to a well thought architecture. This value is maintained if the thought on architecture is not limited to the architecture phase, but rather is a continous process.Bill, you mention diminishing returns on code quality. How do you define code quality, and why does creating good quality code take more time? Good quality code is not bulkier than mediocre code. I think it is effort that is spent thinking on what to code, or how to structure code that is time consuming. If we constantly practice writing good code then this thought process becomes second nature, and it does not take a lot of time. The extra time it does take is worth more than the effort we would have to put in to fix bugs.Is it possible that if programmers had a lot of discipline and dilligence then they would produce good quality code by deault?